Four DLC packs were released for this game (numbered as in the game's files):
- Big Little Character Pack
- Side Quest Character Pack
- The Armory Pack
- The Battle Pack
DLCs 1, 2, and 4 are available to buy on Steam. DLC 3, however, is only purchasable on consoles. Despite this, the DLC's files are actually still included in the game files, and theoretically could be restored by removing all instances of ItemAbility Always "DLC3Item"
from <path-to-game>\Chars\Items_txt\zDLC_3.txt
in an installation with the DAT files extracted (I haven't tested this, but I'm pretty sure someone has already done so). Mentioning this might be a can of worms however, as not only can the unreleased DLC be acquired via modding, but the ones for sale can as well.